The use of integrated circuit modules on printed circuit boards is, of course, well known, as is the combination of integrated circuits and a potentiometer for use in light dimming configurations, motor control configurations, etc. Many of these applications provide SCR's, diacs, or triacs used for controlling alternating current power in response to the setting of the potentiometer.
Most such circuits, if used to control high current loads, generate substantial amounts of heat in the integrated circuit module which must be drawn from the module using any one of a variety of heat sink products. The prior art has also provided for the heat sinking of such integrated circuit elements directly into the front panel of an instrument onto which the potentiometer is mounted.
Thus, the prior art has provided potentiometers combined with integrated circuits wherein the potentiometer mounting bushing has been passed through a hole in a heat sink tab from an integrated circuit to directly mount the heat sink tab, the integrated circuit, and the potentiometer to the front panel of a user's instrument, all through the application of a single potentiometer bushing nut.
Although this prior art configuration has proved satisfactory in most circumstances, the combination has always been hand wired because of the requirement that the heat sink tab of the integrated circuit must abut, in face-to-face relationship, against the user's front panel. This requires a side-by-side configuration of the integrated circuit body and the potentiometer body which would, under normal circumstances, prohibit the use of printed circuit boards which would facilitate automatic part insertion and machine soldering of the entire assembly.
As a consequence of the prior art requirements for hand wiring, prior art combination devices, including a potentiometer wired to control an integrated circuit, particularly for controlling AC current levels, have been relatively high in cost, much of the cost incurred in the hand wiring operation.
The prior art, in the interest of machine insertion and wiring techniques, has, in many instances, utilized separate heat sink elements rather than utilizing the front panel of the user's equipment for heat sinking. By using an alternate heat sink, it is possible to place the heat sink tab of the integrated circuit at a location other than that which will be abuted against the user's front panel, and to thus combine the potentiometer and integrated circuit on a printed circuit board in a conveniently wired fashion. This arrangement, however, requires that a separate heat sink be provided, which heat sink adds to the complexities of the mechanical assembly, since it must be separately mounted on the integrated circuit heat sink tab, and adds to the cost of material. Thus, even this expedient, while reducing the labor costs to some extent, necessarily increases the costs of the combination unit.